The optimum arrangement of the plates in a multi-layered shield

A normal impact of a three-dimensional rigid conical impactor penetrating into a layered shield is studied using a simpli®ed model for an impactor±shield interaction. The shield consists of adjacent plates manufactured from one of two possible materials, and the total thickness of the plates manufactured from every material is given. It is found that advancing any plate inside a shield in the direction of penetration causes a monotone change in the ballistic limit velocity. A criterion for increasing or decreasing of the ballistic limit velocity, which depends on the properties of the materials of the layers in the shield, is determined. A maximum ballistic limit velocity is attained for a two-layered shield without alternating the plates manufactured from di€erent materials